Take Home Final Exam Questions Geology 1207.1 2016 You have been given the task
ID: 297985 • Letter: T
Question
Take Home Final Exam Questions Geology 1207.1 2016
You have been given the task to locate a high level nuclear waste disposal site somewhere in Canada. What would be the criteria for locating a site? How might you test the site before proceeding with construction? What about the social aspects of the disposal site selection, how could these be overcome? What kind of monitoring would have to be done on the site after it started operation to assure health and safety? How would this site compare to a disposal for low level radioactive material? Why has there not been a permanent disposal site in Canada before now? (Give references) Value 33.33%
Explanation / Answer
Basic criteria for locating a high level nuclear waste disposal site is as follows:
(1) A capability to test and monitor components important to safety,
(2) Suitable shielding for radioactive protection under normal and accident conditions,
(3) Confinement structures and systems,
(4) A heat-removal capability having testability and reliability consistent with its importance to safety, and
(5) means to minimize the quantity of radioactive wastes generated.
The disposal site should have some criteria to be selected.They are as follows:
• The waste disposal site cannot be built on landslides which are active or may become active in the future.
• The waste disposal site can only be constructed in areas which do not have an important economic or ecological value.
• Areas should have sufficient size/capacity (at least 1 hectare) to be used as a waste disposal site for a prolonged time.
• The waste disposal site should preferably be located on a terrain with a slope less than 20 degrees.
• The waste disposal site should preferably be located within 2 km from the city limits.
• The waste disposal site should preferably be located at least 300 meters from any existing built-up area.
• The waste disposal site should be constructed on clay-rich soils (preferably more than 50% clay).
• The waste disposal site should have a high soil thickness.
• The waste disposal site’s soil should have a very low permeability (preferably 0.05 meters per day or less).
Some safety measures are to followed for health assurance.They are:
1) Safety manuals must be provided and employees must be instructed in applications and procedures.
2) Communication equipment should be available on site for emergency situations.
3) Qualitative and quantitave records of wastes recieved and location of disposal must be maintained.
4) Source of water should be available on site to reduce fire and dust inconvenience on site.
5) Long term programs must be initiated in order to maintain health and wealth.
Disposal of low level radioactive wastes:
The US Nuclear Regulatory Commission classifies low-level wastes into four categories based on radioactivity corresponding to management and disposal requirments: Class A waste has the lowest radioactivity level and decays to background level after about 100 years. It accounts for about 99% of the volume of LLW generated in the USA and includes slightly contaminated paper products, clothing, rags, mops, equipment and tools, as well as depleted uranium. Class B and C wastes include filters, resins, irradiated hardware with activation products, and longer-lived radioisotopes that decay after 300 and 500 years, respectively. Greater-than-Class C LLW has radionuclide concentration limits greater than those specified for Class C waste.
The disposal of radioactive waste is one of the most challenging environmental problems facing Canada today. Since the Second World War, when Canadian scientists first started to investigate nuclear reactions, there has been a steady accumulation of such waste. Research reactors built in the early postwar years produced small amounts of radioactive material but the volume grew steadily as the nuclear power reactors constructed during the 1960s and 1970s began to spawn used fuel bundles. Although this radioactive refuse has been safely stored for the short term, no permanent disposal system has yet been fully developed and implemented.
Canada is not alone in this regard. A large number of countries use nuclear power reactors but none has yet put in place a method for the long-term disposal of the radioactive waste. Scientists and engineers throughout the world are investigating different possibilities; however, enormous difficulties remain.In Canada, used fuel bundles from nuclear reactors are defined as high-level waste; all other waste created at different stages in the nuclear fuel cycle is classified as low-level. Although disposal of low-level waste is an important issue, it is a more tractable problem than the disposal of high-level waste.
In Canada, the proposed method of disposal is to bury the radioactive waste deep in the rock of the Canadian Shield. This rock formation was chosen for a number of reasons. The Canadian Shield has been stable for at least 600 million years and most of it has not experienced major orgenic (or "mountain-building") activity for 2.5 billion years; it is therefore likely to remain stable for the lifetime of a disposal vault. In disposing of nuclear fuel waste, a difficulty is to develop a system that will be secure for thousands of years. Although it is impossible to guarantee continuing safety, it is possible to develop models that provide a convincing and indirect demonstration that the proposed disposal system provides a sufficient level of safety to both current and future generations.
This lack of certainty about the long-term safety of nuclear waste disposal methods has led some critics to suggest that the high-level waste should remain in storage until scientists have developed better ways of dealing with it effectively. Nevertheless, most countries like Canada included, have decided to proceed with present plans for disposal systems. Canada's proposed method of deep geological burial is the result of many years of scientific and technological research, which is still ongoing. The final form of the disposal system, its site and its possible date for completion are yet to be decided.
In Canada, as in other countries, public consultation on the proposed disposal system has allowed various groups to voice their criticisms of the project. It is hoped that extensive consultation will make public acceptance of the system easier to achieve. So far, Canada has managed to avoid much of the adverse reaction experienced in other countries by not naming a specific disposal site. Despite these future difficulties, the Canadian research program continues to work towards a safe and environmentally acceptable way to dispose of high-level nuclear fuel waste.
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